Internal combustion engine



FIG. 1 is a front perspective view of an internal combustion engineshowing my new design;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a right side elevational view thereof;

FIG. 4 is a left side elevational view thereof; and,

FIG. 5 is a top view thereof.

Th ornamental design for an internal combustion engine, as shown anddescribed.